A prior art headrest folding apparatus is disclosed in Korean Unexamined Patent Application Publication No. 2008-0094385.
Such a prior art headrest folding apparatus includes: a housing 10 that is mounted in a backrest of a seat and has guide recesses 12 whose upper portions are formed to be open at the same upper positions of opposite lateral plates 11 and whose centers are the same as the hinge holes 13; a stay rod 20 that is pivotably installed on the housing by hinge plates 23 whose rear ends are fixed at opposite sides of a horizontal portion 21 thereof and whose front ends are coupled to the respective hinge holes by hinge axles 24; a stay member in which a stay board 31 is mounted wherein the stay board 31 has guide holes 3 into which tips of both vertical portions 22 of the stay rod are inserted and which are formed in parallel at both sides thereof; a holding member 40 which is installed on an inner face of one of the lateral plates 11 by a holding axle 40b so as to be turned in the direction opposite to the stay rod by a repulsive force of a holding spring 40a and which has a holding recess 41 that is formed in an upper portion thereof and that holds the horizontal portion of the stay rod turned upward to be upright when the stay member is pushed upward and a holding step 42 that is formed at a lower end thereof; a brake member 50 which is installed at a lower portion of the inner face of one of the lateral plates 11 by a brake axle 50b so as to be turned in the direction opposite to the holding member by a repulsive force of a brake spring 50a and which has a brake step 51 that is formed at an upper end thereof and catches the holding step when the holding member holds the horizontal portion of the upright stay rod such that the holding member is braked to keep the stay rod upright without causing reverse rotation; a wire 60 which is tied to a rear end of the brake member at one end thereof and to a lever (not shown) installed outside the backrest at the other end thereof, pulls the brake member when the lever is operated, and turns the brake member in the direction opposite to the repulsive force of the brake spring so as to release braking of the holding member; a main spring 70 which is coupled to the hinge axle, which is hooked on the horizontal portion of the stay rod at one end thereof and on the other lateral plate of the housing at the other end thereof, and whose repulsive force is applied to turn and bend the stay rod in a forward and downward direction when the braking of the holding member caused by the brake member is released; and a link 80 whose front end is coupled to hinge segments 312 in the middle of a lower face of the stay board by an axle 81 and whose rear end is coupled to an upper end of a bracket 10a at a middle rear side of the housing by an axle 81′ so as to be located at a rear upper side relative to the hinge axle.
Among reference symbols or numbers, 14′ indicates an axle hole of the brake axle 50b, 17 indicates a stay piece, 16 indicates an insertion hole of the wire 60, 15 indicates a bottom plate, 11a indicates an axle hole of the axle 81′, and 43 indicates a stay step.
This prior art headrest folding apparatus is complicated in structure, and the brake member 50 and the holding member 40 are worn away due to frequent use, which is responsible for a loose gap.
Further, to resolve this problem, a rubber member is installed in front of the brake member 50 and the holding member 40 of the headrest folding apparatus, but it is worn away due to frequent friction, which is also responsible for a loose gap.